The present invention relates to antifungal antibiotics, their production, their pharmaceutical use, and pharmaceutical compositions containing them. More particularly, the antibiotics are produced by Actinomadura hibisca and possess a benzo[a]naphthacene nucleus.
Few examples of benzo[a]naphthacene quinones derived from microbial sources have been reported and these include compounds designated G-2N and G-2A, and KS-619-1. While no biological activity was reported for G-2N and G-2A, KS-619-1 is disclosed as inhibitor of calcium ion and calmodulin-dependent cyclic nucleotide phosphodiesterase. Recently, published European Patent Application 277,621 discloses antifungal antibiotics BU-3608 (Ia), BU-3608 B (Ib), and BU-3608 C (Ic). Antibiotics benanomicins A and B were reported in J. Antibiotics, 1988, 41:807-811; benanomicin B appears to be the same as BU-3608 C whereas benanomicin A has a hydroxyl group in place of the sugar amino group. ##STR1##
Our co-pending application U.S. Ser. No. 203,776, filed Jun. 7, 1988 discloses BU-3608 D (Id) and BU-3608 E (Ie).